JPH0680543B2 - Index signal detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A Industrial Field B Outline of the Invention C Prior Art D Problems to be Solved by the Invention E Means for Solving Problems F Action G Example G ₁ Playback of video signal and PCM audio signal and index signal Explanation of detection (Fig. 1) G ₂ Explanation of tape feed control (Figs. 1 and 2) G ₃ Explanation of other examples (Fig. 3) G ₄ Explanation of other examples H Effect of the invention A Industrial BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an index signal detecting device such as a cue signal recorded in a track area separate from a video signal and PCM audio data in a rotary head type recording / reproducing device such as an 8 mm video.

B. Summary of the Invention The present invention is a device for detecting an index signal recorded in a track area separate from an information signal such as a video signal by a rotary head during high speed reproduction. It is designed to be swung in a direction intersecting with the scanning direction so that the rotary head can always pick up the index signal during high speed reproduction.

C Conventional technology In the case of 8 mm video, in addition to the mode in which the audio signal is frequency-modulated and mixed with the color video signal in a state where it can be separated in terms of frequency, the audio signal is optionally converted into a PCM and converted into a color video signal. Is divided into regions and one track is formed by both of them to record.

FIG. 4 shows an example of a rotary head device for 8 mm video,
FIG. 5 shows the tape format.

In FIG. 4, HA and HB are rotary magnetic heads for recording and reproduction, and these heads HA and HB are mounted so that the azimuth angles of their working gaps are different from each other and they are angularly separated by 180 °. The drum (1) is rotated in the direction of the arrow (3H) at the frame frequency (30Hz) while slightly protruding from the peripheral surface. Then, the magnetic tape (2) is circulated in the angular range of 221 ° with respect to the peripheral surface of the drum (1), and is run at a constant speed in the direction of the arrow (3T).

Therefore, on the tape (2), as shown in FIG. 5, the tracks (4
A) and (4B) are alternately formed to record a signal, but among the tracks (4A) and (4B), the rotary head HA and
The audio signal related to one field of the video signal is converted into PCM in the area AP of the angular range of about 36 degrees (including the after-recording margin and the guard band for the PCM audio signal) from the time when HB starts scanning. The area AV is recorded in a time-axis-compressed state and then covers an angular range of 180 degrees.
In this area, a color video signal for one field, an FM audio signal, and a tracking signal are recorded. The remaining 5 ° is a margin period when the head is separated from the tape.

As described above, since it is possible to record and reproduce PCM audio signals in 8 mm video, paying particular attention to this point, the recording area AV of color video signals is also used for PCM audio signal recording, and 8 mm video is recorded. A technique has been proposed which enables it to be used as a recording / reproducing device exclusively for PCM audio (see Japanese Patent Laid-Open No. 58-222402).

That is, since the area AV for the 180 ° angular range where the video signal and the like are recorded is five times as long as the PCM area AP for the 36 ° angular range, the area AV is divided into five equal parts. As shown in Figure 6,
Per truck (4A), (4B)
Providing five divided track areas AP ₂ ~AP ₆ shown in another track area AP ₁ of the PCM audio signals with ~. And
The six respective one channel PCM audio signal of the divided track areas AP ₁ ～AP _6, i.e. to record one field period signal PCM turned into time-base-compressed audio signal, and is to be reproduced .

Therefore, in this case, the audio signal for one channel can be recorded and reproduced for each area unit, so that the audio signal for six channels can be recorded and reproduced, which is six times as long as the conventional recording time ( Capacity) can be obtained (hereinafter, this technology is referred to as multi-PCM).

And, the processing circuit of the PCM signal in the case of this multi-PCM is
Considering recording / reproducing for each divided track area unit, a processing circuit for one channel included in the conventional 8 mm video may be used.

By the way, the track format of the 8 mm video described above will be described in more detail as shown in FIG. That is, in the figure, from the right side where the rotary head starts to contact the tape (2), first, the rotation angle of the head at the tip portion is 5 degrees, and the protrusion portion (11) is defined as the protrusion portion (11). 2.06
A period (corresponding to 3H (H is a horizontal period) of the video signal) is a preamble part (12) which is a part of a clock line synchronized with the subsequent PCM data. Following this preamble part (12), a recording area (13) for PCM data of a time axis-compressed audio signal is provided over 26.32 degrees. 2.06 degrees (3
During the period H), the postamble part (1
4) and then 2.62 degrees is used as a guard section (15) for the video signal section and the PCM data section. Following this guard section (15), a recording area (16) for one field of video signal is provided over 180 degrees. Further, the subsequent 5 degrees is set as the separating portion (17).

Further, FIG. 8 shows the track format in the case of multi-PCM, and when looking at one divided track area for PCM audio signal, it is exactly the same as the PCM audio area of the normal 8 mm video track format in FIG. The inrush section (21), preamble section (22), PCM data section (23), postamble section (24), and guard section (25) are assigned to each of the divided track areas AP _{1 to} AP _6. It is designed to be used.

The PCM data is recorded on the tape with the data of "1" and "0" modulated, but for 8 mm video, for example, the data of "1" is 5.8 MHz and the data of "0" is 2.9 MHz. Is modulated and recorded. And, in the preamble part (12) or (22) and the postamble part (14) or (24), conventionally, all the data is "1", that is, 5.8M.
The Hz signal is recorded.

By the way, in the above-mentioned 8 mm video and multi-PCM, as a so-called cueing method, an index signal is recorded in, for example, the postamble part (14) or (24) in each track format described above and the index signal is recorded. The present applicant has previously proposed what is used for cueing (Japanese Patent Application No. 60-64554).

According to the previously proposed invention, the rotary head can record and reproduce the index signal, there is no need to provide a fixed dedicated head, and the index signal can be easily input or erased later. There are features.

D Problem to be Solved by the Invention By the way, the indexing using the index signal recorded as described above is performed by so-called high-speed reproduction in which the tape is fed at high speed. In this case, the rotary head scans across a plurality of recording tracks as shown in FIG.

Since the azimuth angle of the working gap is different between the rotary heads HA and HB, during high speed playback, each head HA, HB discards the playback signal from only one of the corresponding tracks (4A) (4B). Absent. Therefore, the reproduction outputs of both heads HA and HB are as shown in FIGS. 10A and 10B. That is, in FIG. 10, TA indicates scanning of the head HA, TB indicates scanning of the head HB, and the envelope waveform of the head output in each scanning TA and TB is shown in the figure.

Here, at the time of this high-speed reproduction, even if the drum position servo is applied to the rotary heads HA and HB, tracking servo is not applied, so the scanning position of the rotary head with respect to the recording track pattern is not fixed. However, after the high-speed reproduction is started and the tape is started, the scanning phase of the rotary head with respect to the recording track pattern is fixed, and the envelope waveform is repeated at a cycle corresponding to the scanning phase.

FIG. 10A shows the envelope waveform of the head output at a certain scanning phase when the tape speed is an even multiple of the normal reproduction speed, and FIG. 10B shows when the tape speed is a radix multiple of the normal speed. An example of the envelope waveform of the head output in a specific scanning phase is shown. As described above, when the tape element is exactly an integral multiple of the normal value, as shown in FIGS. 10A and 10B, the envelope waveforms of the reproduction outputs of the heads HA and HB are exactly the same. On the other hand, when an offset α that is an integral multiple ± α (0 <α <1) is added instead of an integral multiple speed, an envelope waveform that repeats at a predetermined cycle is obtained. For example α =
If ± 1/2, the envelope waveform is repeated every two rotations (four scans) as shown in FIG. 10C, and α = ±
If it is 1/4, the envelope waveform will be repeated every 4 rotations (8 scans).

By the way, in the case where the envelope waveforms are the same for both heads HA and HB, as in the case of the odd-numbered speed envelope waveform in FIG. 10B, when the rotary head scans the index area part, that head is At the position where the tracks having different azimuth angles are scanned, the envelope output becomes almost zero as shown by the hatched lines in FIG. 10B, and the index signal cannot be reproduced at all. In addition, even speed (10th
In the case of FIG. A), if the hatched portion in FIG. A is the index area, no index signal can be picked up from the reproduction output of one head.

This can be avoided if the tape speed is given a specific offset α as shown in FIGS. 10C and D. That is,
As shown by hatching in FIGS. 6C and 6D, even if the reproduction output becomes zero in one scan in the index area, it is always reproduced in a predetermined level or higher in the other area in the other scan. This is because the output can be obtained.

However, in order to give such an offset α, it is necessary to feed the tape with a capstan at the time of high-speed reproduction, and there is a drawback that the speed control becomes difficult as the tape speed becomes higher due to slips or the like.

Further, as another method for avoiding the head output from the index area becoming zero at the above-mentioned integer multiple speed, the scanning phase is controlled so that the scanning phase does not become the head output from the index area becoming zero. However, in that case, the servo of the reel motor or the servo of the capstan motor is required when the tape is fed to the capstan, and the multi-PCM
In this case, it is difficult to apply this method.

E Means for Solving the Problems In the present invention, during high speed reproduction, the rotary head is oscillated relative to the tape in a direction intersecting the scanning direction.

F action During high-speed playback, the rotary head is oscillating relative to the tape in the envelope of the output of the rotary head, so the index area does not always become zero. The index signal output of a certain level or higher can be picked up from the index area, and the detection probability of the index signal becomes uniform regardless of the scanning phase of the rotary head with respect to the recording track pattern.

G. Embodiment FIG. 1 is a block diagram of an example of a reproducing apparatus to which an example of the present invention is applied, and this example is an example in the case of the above 8 mm video.

Description in G ₁ reproduced video signal and the PCM audio signal and the index signal detector (31) switching a head change-over switch circuit, the switching signal PFSW in the state of FIG. And the state of the alternately inverted every half rotation period To be

(32) is a switching signal P for 8 mm video and multi-PCM
This is a switch for switching the FSW. That is, 8
At the time of milli video, this switch (32) is switched to the N side.

Then, the rotary head HA, a drum motor for driving the HA (41)
Is provided with a pulse generator (42) for obtaining one pulse per one rotation of the rotary head HA and the pulse generator (42).
A 30 Hz pulse PG indicating the absolute rotation phase of HB is supplied to the head switching signal forming circuit (43) to obtain a rectangular wave signal SC with a duty of 50%, and this rectangular wave signal SC is a switching signal.
Switch circuit (32) through switch (34) as RFSW
And (33).

Also, when multi-PCM, this switch (34) is switched to the M side. Then, at this time, the rectangular wave signal SC from the forming circuit (43) is supplied to the phase shift circuit (44), and the rectangular wave signal SC is supplied in accordance with the divided track area designated by this.
Integers but 36 ° × (n-0) (n is in accordance with the number of the divided track area, n = 2 when the case n = 1, AP ₂ for AP _1, ......
The phase is shifted by n = 6 when AP ₆ 6), and the shifted signal is fed through the switch (32) to the switching signal RFSW.
Is supplied to the switch circuits (32) (33). In addition,
The switching signal RFSW is supplied to the timing signal forming circuit (45) to form a PCM area signal indicating the designated divided track area, and the PCM audio reproduction processing circuit (55).
Is supplied to.

Next, description will be made regarding the reproducing operation. During this reproducing operation, although not shown, the drum phase servo based on the signal PG is applied.

During normal reproduction, the reproduction signal outputs from the heads HA and HB are reproduced amplifiers (51A) and (51A), respectively.
Is supplied to the switch circuit (31) via B), and the switch circuit (31) is switched by the switching signal RFSW so that the video signal and the FM audio signal from the area AV are the video and FM audio reproduction processing circuit (52). ),
PCM audio playback processing circuit for PCM data in area AP (55)
, Respectively.

Then, in the video signal system and the FM audio reproduction processing circuit (52), the video signal is demodulated and output to the output terminal (53), and the FM audio signal is demodulated and the demodulated output is output to the output terminal (54). To be done.

On the other hand, in the PCM audio reproduction processing route (55), the reproduction signal is waveform-shaped by the digital signal reproduction circuit (56) into digital data of "1" and "0", and then the PCM processing circuit (57).
Is supplied to, and demodulated, and subjected to error detection, error correction, etc., and then returned to the left and right channel analog audio signals, which are led to output terminals (58L) and (58R).

During multi-PCM playback, the switching signal RFSW is phase-shifted according to the designated divided track area, and the head HA and
The signal picked up by the HB is supplied to the PCM audio reproduction processing circuit (55), and the audio signal is reproduced in the same manner as described above. At this time, although not shown, the output of the video and FM audio reproduction system (52) is muted.

Then, in the case of detecting the index signal during high-speed reproduction, the drum phase servo is applied to the heads HA and HB at this time as well. Therefore, the switching signal RFSW is obtained in exactly the same manner as in the normal reproduction and the multi-PCM reproduction, and the PCM area signal SA is obtained from the timing signal forming circuit (45), and the PCM area is reproduced in the PCM audio reproduction processing circuit (55). The signal reproduced from is supplied from the switch circuit (31).

Then, at this time, a signal from the digital signal reproducing circuit (56) is supplied to the gate circuit (61), and at the same time, the timing signal forming circuit (45) scans the index area portion by the heads HA and HB. A signal for opening (61) is supplied, and a reproduction output in the index areas of the heads HA, HB is obtained from this gate circuit (61). The output of this gate circuit (61) is the demodulation circuit (6
2) and demodulated into "0" and "1" data,
The demodulated data is "0" detection circuit (63) and counter (6
4) is supplied to the index signal detection circuit (65). In the detection circuit (65), for example, when it is detected that "0" data continues for a predetermined number or more, the detection output of the index signal is obtained.

Description of G ₂ tape feed control (71) is a capstan, and the tape (2) is held by the capstan and the pinch roller (72) to transfer the tape (2).

(73) is a capstan drive motor, and the tape speed is switched between normal reproduction and high speed reproduction as follows.

That is, (76) is a changeover switch circuit for that purpose, which is switched to the N side during normal reproduction and to the V side during high speed reproduction.

A frequency generator (74) that obtains a frequency signal FG according to the rotation speed of the motor (73) is provided on the rotation shaft of the capstan drive motor (73).
Is supplied to one input terminal N of the switch circuit (76) through the amplifier (75), and the frequency signal FG that has passed through the amplifier (75) also passes through the frequency divider circuit (77) to the other side of the switch circuit (76). Is supplied to the input terminal V of.

Then, the output of the switch circuit (76) is supplied to the servo circuit (78), and a motor drive control voltage is obtained from this, which is the motor drive circuit (79) and the adder circuit (8).
0), capstan motor (73) via amplifier (81)
Is supplied to.

The switch circuit (76) is switched by the mode signal MD from the terminal (83).

That is, during normal playback, this mode signal
MD is, for example, "0", the switch circuit (76) is switched to the input terminal N side, and the switch circuit (84) described later is turned off. Therefore, during this normal playback, the frequency signal FG
Is supplied to the servo circuit (78) as it is, and the capstan motor (73) is set so that this signal FG has a constant frequency fo.
A speed servo is applied to the tape (2) and the tape (2) is transferred at the normal reproduction speed.

Next, during high speed reproduction, the mode signal MD becomes "1" and the switch circuit (76) is switched to the input terminal V. Further, since the mode signal MD is supplied to the division ratio setting circuit (82), the division ratio 1 / n of the division circuit (77) is set by the setting circuit (82) during the high speed reproduction. To be done. Therefore, at this time, the frequency signal FG is output from the switch circuit (76).
Is divided by 1 / n, the signal is supplied to the servo circuit (78), and the speed of the capstan motor (73) is adjusted so that the divided signal has a constant frequency fo. Servo is applied. That is, the tape is transported at a tape speed n times that in normal reproduction.

Further, during the high speed reproduction, the switch circuit (84) is turned on by the mode signal MD. Then, the random signal is supplied from the random signal generator (85) to the addition circuit (80) and is superimposed on the motor drive voltage. This random signal becomes a disturbance of the motor rotation, and the tape (2)
Is not a constant velocity and is disturbed by this disturbance. For this reason, the loci of the rotary heads HA and HB on the tape are not linear, and the tracks are oscillated by a disturbance in a direction intersecting with the operation direction.

In general, the index signal is written for 3 to 10 seconds at normal speed. Therefore, if the index signal is oscillated as described above, at least one area of a plurality of tracks for 3 to 10 seconds is recorded. The index signal can be detected at a certain level or higher, and the head output does not always become zero as in the conventional case.

In the example shown in FIG. 1, a disturbance is added to the motor drive voltage, but as shown in FIG. 2, the servo circuit (78)
A random signal may be added to the above output voltage through the switch circuit (84) in the addition circuit (86) during high speed reproduction. Further, it is not necessary to give a random signal as the disturbance, and the essential point is that the signal is uncorrelated with the rotation cycle of the motor.

G ₃ Description of other examples To give disturbance to the rotation of the capstan motor during high-speed reproduction, the following may be performed.

That is, FIG. 2 is an example of a reproducing system including another example of the present invention. In this example, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In this example, no special signal source for disturbance is provided unlike the example of FIG. In this example, during high-speed reproduction, the frequency division ratio set by the frequency division ratio setting circuit (82) is alternated between 1 / N and 1 / M at a cycle of, for example, several times to several ten times the vertical frequency. Try to change. That is, for example, if it is changed in 6 vertical cycles, the frequency division ratio is switched to 1 / N and 1 / M (N ≠ M) every 3 rotations of the rotary heads HA and HB.

By doing so, the tape is transferred alternately at N times speed and M times speed every three rotations of the head, and the same effect as in the example of FIG. 1 is obtained.

The cycle for changing the frequency division ratio is determined according to the response speed of the capstan motor.

In the case of this example, the signal source for the special disturbance as in the example of FIG. 1 is not required, and the setting of the frequency division ratio can be controlled by the microcomputer, so there is no cost increase and this It can be easily realized in terms of points.

G ₄ Explanation of other examples In the above example, during high-speed search, the frequency signal FG is divided and the speed servo is applied by the divided signal.
This is so that the reproduced image of the video signal can be obtained during this high speed search, and such a servo may be applied during the high speed search for index detection. That is, a constant voltage may be applied to the motor to free-run, the tape may be transferred at high speed, and disturbance may be applied.

When the servo is applied as described above, when the high speed reproduction of the video signal is performed and the index signal is not detected, the switch circuit (84) is turned off and the index signal is detected. Only the switch circuit (84) may be turned on.

Further, although the above example is an example in which the capstan motor is controlled, it is of course applicable to the case in which the reel motor is controlled.

Further, in the present invention, instead of controlling the tape transfer speed, the rotary head is arranged on, for example, a bimorph plate, and a control voltage is applied to this bimorph plate to provide a control voltage to each head at a predetermined cycle or at random during high speed reproduction. May swing in a direction orthogonal to the scanning direction.

As the index signal, in the above example, the postamble signal is 5.8 MHz, which is the data of "1".
Although the 2.9 MHz signal which is the data of “0” is used, the signal of the pattern which does not appear as data is not limited to this and may be used.

Further, it is of course possible to record coding data as an index signal. When coded in this way, not only the beginning of the song but also data indicating the inside of the song, other tape speed, time information, etc. can be recorded as an index signal.

Further, the present invention is not limited to the case of 8 mm video, but can be applied to the index detecting device of the rotary head type reproducing device.

As described above, according to the present invention, at the time of high-speed search, the rotary head swings on the tape in a direction intersecting the scanning direction without drawing a definite scanning locus with respect to the recording track pattern. Since the scanning is performed as described above, the head output in the recording area portion of the index signal can be prevented from always becoming zero, and the detection probability of the index signal can be made uniform.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of a reproducing apparatus to which an example of the present invention is applied, and FIG. 2 is a block diagram of another example of a main part thereof.
FIG. 3 is a block diagram of an example of a reproducing apparatus to which another example of the present invention is applied, and FIG. 4 is a diagram showing an example of a rotary head device of an apparatus to which the present invention is applied, FIGS. 5 and 6. Shows the recording track pattern, FIGS. 7 and 8 show the specific track format, and FIG. 9 shows the scanning locus of the head during high-speed reproduction. The figure is a diagram for explaining the head output during high-speed reproduction. HA and HB are rotary heads, (2) is a magnetic tape, (65) is an index signal detection circuit, (71) is a capstan motor, and (85) is a signal source of random signals.

Claims (1)

[Claims] 1. An information signal is recorded by a rotary head as one track every predetermined time, and an index signal for the information signal track is recorded in an area which does not overlap the recording position of the information signal by the rotary head. In a device for detecting the index signal by moving the recorded recording medium at a speed higher than that at the time of recording and performing high speed reproduction, at the time of the high speed reproduction, the rotary head is moved relative to the tape in the scanning direction. An index signal detecting device that is oscillated in a direction intersecting with.